The present invention relates to medical equipment, techniques and procedures, and more particularly, to the circulation and recovery of blood during and immediately following heart bypass and similar surgery involving a cardiopulmonary bypass circuit (CPB) or more generally, an extracorporeal blood circuit (ECC).
A persistent dilemma is faced thousands of times each day worldwide, of how to handle the volume of a patient's blood in the ECC after the surgical procedure has been completed and the patient is disconnected from the circuit.
Significant improvements toward achieving this goal have already been implemented using the Hemobag® techniques described in the present inventor's U.S. Pat. Nos. 5,928,178; 6,398,751; 7,033,334; and 7,402,278, the entire disclosures of which are hereby incorporated by reference. A substantial volume of concentrated whole blood can be quickly and easily recovered from the ECC immediately following, i.e., cardiac, thoracic, or vascular surgery. Most of the blood in the ECC circuit flows into a blood reservoir, preferably a dedicated blood bag, and hemoconcentrated in the blood reservoir while connected in a sub circuit of the ECC.
In addition to the recovery of a patient's blood following surgery, a related concern is the management of the fluid volume in the ECC and in the patient during surgery. The volume of fluid circulated to the patient during surgery over the course of several hours must be varied to correspond with the particular stages in the surgery and the patient's physiology. Make-up fluid or volume (crystalloid, colloid or blood product) is required when the overall need or blood concentration in the ECC and the patient needs correction for stabilization. This large amount of diluted blood increases the time necessary for recovery of the patient's whole blood after surgery.
Extracorporeal circuits can be necessary after surgery, for example in the critical intensive care or ICU where the patient relies on the ECC for a period of days rather than hours and are referred to as ECMO or VADS. The concentration of blood in the patient and the circuit, and the total volume of fluid in the patient plus the circuit can vary considerably, and it is important that the fluid volume management be closely monitored.
Presently, fluid management is rather varied and implemented by opening and closing clamps into and out of the venous reservoir of the ECC. Regardless of any other components that may be fluidly aligned, when the venous reservoir is fluidly connected in series along the fluid path along the cannula line from the patient and the cannula line to the patient, the venous reservoir acts imprecisely as an in-line accumulator of fluid or volume when the flow to the patient is to be decreased and as a source of fluid volume when flow to the patient is to be restored or increased.